Tendon and ligament tears are common in sports injuries and trauma. Surgical repair of the tears can be invasive with many possible complications, including painful adhesions of scar tissue. Most patients are conservatively treated with immobilization. Only about 35% of orthopaedic trauma cases are treated surgically.
Many bone anchors have been studied and developed to reattach torn tissues. In general, metallic and non-degradable polymeric anchors or staples can fasten torn tissues well; but with time, the non-degradable device can migrate into undesirable places, such as joints. On the other hand, Suretac™ is degradable and easily deployed; however failure due to low pull out strength is a common concern. U.S. Pat. Nos. 4,884,572 and 4,895,148 issued on Dec. 5, 1989 and Jan. 23, 1990 respectively by F. Barry Bays are related to a tissue repairing tack similar to Suretac™ in the market. The tack contains a head, a cylindrical shaft with barbs and a lumen open from the head to the distal end of the shaft. For delivery of the tack, a needle is inserted into the lumen and protruded beyond the distal end of the shaft of the tack. The needle carrying the tack pierces through the torn tissue into bone. The barbs of the tack engage with bone tissue to hold the torn tissue in place. The needle is then withdrawn from the bone and the tack. The tissue gripping strength of the barbs or threads of the tack is very limited, especially in poor quality bone. Therefore, the pull out strength of the tack is generally low. Healing of the torn tissue requires secure contact to the cancellous bone. The low pull out strength often contributes to tack loosening, forming a gap between the bone and supposedly reattached tissue. As a result, tissue reattachment is unsuccessful; weakness and pain persist.